A224502 Prime numbers (together with one) whose representation in balanced ternary are palindromes.
1, 7, 13, 43, 61, 73, 103, 367, 421, 457, 547, 601, 613, 757, 859, 1039, 1093, 3823, 4021, 4561, 4723, 4759, 5743, 6211, 6373, 6481, 6949, 7219, 7489, 7933, 8563, 8941, 9103, 9679, 29527, 30013, 31147, 31741, 33037, 35251, 36061, 36097, 36583, 37717, 39607, 41011, 42667, 43963, 44773, 45691, 47581, 49201
Offset: 1
Examples
For n=5, a(5)=61 and in balanced ternary notation is 1ī1ī1.
Links
- Malachi de Ælfweald and Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 199 terms from Malachi de Ælfweald)
- Wikipedia, Balanced ternary
Programs
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PARI
bt(k,n)={ sum(i=0,(n-1)\2, my(t=k%3-1); k\=3; n--; if(n==i,3^n,3^i+3^n)*t ) }; do(N)={ my(v=List([1]),t); for(n=1,N, forstep(k=2,3^((n+1)\2)-1,3, t=bt(k,n); if(isprime(t),listput(v,t)) ) ); vecsort(Vec(v)) }; \\ Charles R Greathouse IV, Apr 08 2013
Comments